In the Linux kernel, the following vulnerability has been resolved: bridge: Fix sleep in atomic context in sysfs path Since the start of the git… (CVE-2026-63988)
A vulnerability in the Linux kernel bridge subsystem was fixed that involved improper locking in the brport_store() function. The issue caused a sleeping function to be called from an atomic context, which is invalid and leads to kernel bugs. The problem arose because the bridge lock was held too broadly when processing sysfs attributes, including those that triggered dev_set_promiscuity(), a function that can sleep. The fix reduces the scope of the bridge lock to only STP-related attributes that require it, preventing the invalid sleep call.
AI Analysis
Technical Summary
The Linux kernel bridge code's brport_store() function historically acquired the bridge lock for all sysfs attribute changes. This lock protects STP state but was unnecessarily held for many attributes that do not require it. Some of these attributes trigger dev_set_promiscuity(), which can sleep. Holding the bridge lock during this call caused a BUG due to sleeping in atomic context. The patch narrows the locking scope to only STP-related attributes, eliminating the invalid sleep scenario and preventing kernel crashes.
Potential Impact
This vulnerability causes kernel BUGs due to sleeping functions being called from atomic context, which can lead to system instability or crashes. There is no indication of remote code execution or privilege escalation from the provided data. The impact is primarily on system reliability and stability when certain bridge sysfs attributes are modified.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The vulnerability has been resolved in the Linux kernel source code by narrowing the locking scope in brport_store(). Users should apply the official Linux kernel updates containing this fix once available.
In the Linux kernel, the following vulnerability has been resolved: bridge: Fix sleep in atomic context in sysfs path Since the start of the git… (CVE-2026-63988)
Description
A vulnerability in the Linux kernel bridge subsystem was fixed that involved improper locking in the brport_store() function. The issue caused a sleeping function to be called from an atomic context, which is invalid and leads to kernel bugs. The problem arose because the bridge lock was held too broadly when processing sysfs attributes, including those that triggered dev_set_promiscuity(), a function that can sleep. The fix reduces the scope of the bridge lock to only STP-related attributes that require it, preventing the invalid sleep call.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel bridge code's brport_store() function historically acquired the bridge lock for all sysfs attribute changes. This lock protects STP state but was unnecessarily held for many attributes that do not require it. Some of these attributes trigger dev_set_promiscuity(), which can sleep. Holding the bridge lock during this call caused a BUG due to sleeping in atomic context. The patch narrows the locking scope to only STP-related attributes, eliminating the invalid sleep scenario and preventing kernel crashes.
Potential Impact
This vulnerability causes kernel BUGs due to sleeping functions being called from atomic context, which can lead to system instability or crashes. There is no indication of remote code execution or privilege escalation from the provided data. The impact is primarily on system reliability and stability when certain bridge sysfs attributes are modified.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The vulnerability has been resolved in the Linux kernel source code by narrowing the locking scope in brport_store(). Users should apply the official Linux kernel updates containing this fix once available.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-qqj9-pc4p-85gc
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-63988"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27aa2a4a8d598912dbd2
Added to database: 07/19/2026, 19:38:18 UTC
Last enriched: 07/19/2026, 20:00:47 UTC
Last updated: 07/20/2026, 17:43:10 UTC
Views: 14
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